High-fidelity transmission of entanglement over a high-loss free-space channel

Alessandro Fedrizzi, Rupert Ursin, Thomas Herbst, Matteo Nespoli, Robert Prevedel, Thomas Scheidl, Felix Tiefenbacher, Thomas Jennewein, Anton Zeilinger

Research output: Contribution to journalArticle

125 Citations (Scopus)

Abstract

Quantum entanglement enables tasks not possible in classical physics. Many quantum communication protocols(1) require the distribution of entangled states between distant parties. Here, we experimentally demonstrate the successful transmission of an entangled photon pair over a 144 km free-space link. The received entangled states have excellent, noise-limited fidelity, even though they are exposed to extreme attenuation dominated by turbulent atmospheric effects. The total channel loss of 64 dB corresponds to the estimated attenuation regime for a two-photon satellite communication scenario. We confirm that the received two-photon states are still highly entangled by violating the Clauser-Horne-Shimony-Holt inequality by more than five standard deviations. From a fundamental point of view, our results show that the photons are subject to virtually no decoherence during their 0.5-ms-long flight through air, which is encouraging for future worldwide quantum communication scenarios.

Original languageEnglish
Pages (from-to)389-392
Number of pages4
JournalNature Physics
Volume5
Issue number6
DOIs
Publication statusPublished - Jun 2009

Keywords

  • QUANTUM KEY DISTRIBUTION
  • SINGLE-PHOTON DETECTORS
  • COMMUNICATION
  • FIBER

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